The present invention relates to packing machines in general, and more particularly to improvements in packing machines which can be utilized for the making of cigarette packs or the like. Still more particularly, the invention relates to improvements in means for manipulating blanks which are converted into envelopes for blocks or other arrays of articles of the tobacco processing industry. Such articles can include cigarettes, cigarillos, cigars, cheroots and the like.
Commonly owned U.S. Pat. No. 3,956,870 granted May 18, 1976 to Friedel Kruse et al. (the disclosure of this patent is incorporated herein by reference) discloses a cigarette packing machine wherein a first turret-shaped rotary conveyor carries an annulus of equidistant hollow mandrels for blocks of parallel cigarettes and receives such blocks at a first transfer station from a condensing or compacting conveyor which, in turn, receives uncompressed blocks from the pockets of an endless chain conveyor. The first transfer station is followed by a station where a pivotable tongs or another suitable supplying device delivers blanks into the spaces between successive mandrels. The blanks are caused to bear against the front sides of the oncoming mandrels by devices which are disclosed, for example, in commonly owned U.S. Pat. No. 3,750,676 granted Aug. 7, 1973 to Friedel Kruse et al. The thus held blanks are thereupon subjected to the action of suitable draping, folding and tucking instrumentalities which convert each blank into an envelope surrounding all but one (open) side of the respective mandrel. The blocks of cigarettes are expelled from the respective mandrels by pushers which enter by way of the respective open sides, and the blocks strip the respective envelopes off the corresponding mandrels for transfer onto a second conveyor at a second transfer station. The machine which embodies the features of the aforediscussed patented machines is manufactured by the assignee of the present application and is known as COMPAS. The first conveyor is caused to advance stepwise and each mandrel is first draped into a first blank which consists of a metallic foil. The thus obtained first envelope is thereupon confined in a second envelope obtained from a second blank which is draped around the first envelope, i.e., around the respective mandrel, and which can be made of paper, cardboard, synthetic plastic sheet material or the like. The means for holding the freshly supplied first and second blanks against the respective mandrels comprises pivotable holders which are designed to urge the blanks against the front sides of the respective trailing mandrels, as considered in the direction of travel of the turret. Each pivotable holder is movable between a first position in which it is remote from the adjacent mandrels and a second position in which it bears against the freshly supplied blank at the front side of the upstream or trailing mandrel. Each second blank is coated with a suitable adhesive at the locations where its portions are to overlap and adhere to each other, particularly at the rear side of the respective mandrel. This creates problems when the material of the second blanks exhibits a strong tendency to reassume its original shape, i.e., the second envelope opens up, especially at the rear side of the mandrel, and the corresponding pack must be discarded. This is particularly undesirable in modern high-speed packing machines which are designed to turn out very large numbers of packs per unit of time (e.g., 400 packs per minute), i.e., in machines wherein the ejection of a relatively small number of packs per unit of time amounts to pronounced losses in output. Another reason for the opening of seams of second envelopes on packs which are produced in such machines is that the intervals of time which are allotted for setting of the adhesive between overlapping portions of the second blanks are extremely short.